The most widely accepted explanation for the ascent of sap in trees is
Correct answer: D. Transpiration cohesion theory of Dixon
- A. Capillarity
- B. Roll of atmospheric pressure
- C. Pulsating action of' living cells
- D. Transpiration cohesion theory of Dixon
Explanation
The transpiration cohesion theory states that water molecules in the xylem of a tree are held together by cohesion, or the attraction between water molecules. The water molecules are also attracted to the walls of the xylem vessels, creating tension. The tension in the water column is what pulls the water up the tree.
Last updated
About Digestion
The human digestive system covers the organs from mouth to anus, the movement of food, and the mechanical and chemical breakdown of carbohydrates, proteins and fats. It also includes the roles of digestive enzymes, bile, absorption through intestinal villi, and the assimilation of nutrients by body cells.
Practise Digestion
680 free Digestion MCQs from Biology, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Biology questions like this
Biology is on 6 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
Related questions
A/An _ is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation if oxygen is absent.
A cavity bounded by ribs and diaphragram is called:
A complex cartilaginous structure surrounding the upper end of the trachea:
A condition with abnormal amount of fats is called:
A hormone called _ controls the secretion of gastric juice.